UPDATE t1 LEFT JOIN t2 ON t2.id = t1.id SET t1.col1 = newvalue WHERE t2.id IS NULL
UPDATE T1, T2, [INNER JOIN | LEFT JOIN] T1 ON T1.C1 = T2. C1 SET T1.C2 = T2.C2, T2.C3 = expr WHERE condition
SELECT Student_details.*, Attendance.* FROM Student_details LEFT JOIN Attendance ON Student_details.s_id = Attendance.s_id;